Modulation of PPAR subtype selectivity. Part 2: Transforming PPARα/γ dual agonist into α selective PPAR agonist through bioisosteric modification

Article abstract of DOI:10.1016/j.bmcl.2010.12.032

A novel series of oxime containing benzyl-1,3-dioxane-r-2-carboxylic acid derivatives (6a-k) were designed as selective PPARα agonists, through bioisosteric modification in the lipophilic tail region of PPARα/γ dual agonist. Some of the test compounds (6a

Full text of DOI:10.1016/j.bmcl.2010.12.032

Bioorganic & Medicinal Chemistry Letters 21 (2011) 628–632
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Modulation of PPAR subtype selectivity. Part 2: Transforming PPARa/c dual
agonist into
a
selective PPAR agonist through bioisosteric modification q
Pandurang Zaware a,b, Shailesh R. Shah b, , Harikishore Pingali a, Pankaj Makadia a, Baban Thube a,
Suresh Pola a, Darshit Patel a, Priyanka Priyadarshini a, Dinesh Suthar a, Maanan Shah a, Jeevankumar Jamili a,
Kalapatapu V. V. M. Sairam a, Suresh Giri a, Lala Patel a, Harilal Patel a, Hareshkumar Sudani a, Hiren Patel a,
⇑
Mukul Jain a, Pankaj Patel a, Rajesh Bahekar a,
⇑
a Zydus Research Centre, Sarkhej-Bavla N.H 8A Moraiya, Ahmedabad 382 210, India
b Department of Chemistry, Faculty of Science, M.S. University of Baroda, Vadodara 390 002, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel series of oxime containing benzyl-1,3-dioxane-r-2-carboxylic acid derivatives (6a–k) were
Received 13 October 2010
Revised 4 December 2010
Accepted 7 December 2010
Available online 10 December 2010
designed as selective PPAR
a
agonists, through bioisosteric modification in the lipophilic tail region of
dual agonist. Some of the test compounds (6a, 6b, 6c and 6f) showed high selectivity towards
over PPAR in vitro. Further, highly potent and selective PPAR agonist 6c exhibited significant
PPAR
PPAR
a
a
/c
c
a
antihyperglycemic and antihyperlipidemic activity in vivo, along with its improved pharmacokinetic pro-
file. Favorable in-silico interaction of 6c with PPAR binding pocket correlate its in vitro selectivity profile
toward PPAR over PPAR . Together, these results confirm discovery of novel series of oxime based selec-
tive PPAR agonists for the safe and effective treatment of various metabolic disorders.
Ó 2010 Elsevier Ltd. All rights reserved.
a
Keywords:
Oxime
1,3-Dioxane-r-2-carboxylic acid
PPAR agonist
a
c
a
Type-2 diabetes
Metabolic disorders
Peroxisome proliferator-activated receptors (PPARs) are ligand-
activated transcription factors belonging to the nuclear hormone
receptor superfamily. The PPAR subfamily consists of three iso-
PPAR
ment of diabetes. However side effects such as heart failure, fluid
retention, and weight gain in patients treated with PPAR selective
c agonists, which are in practice since a decade for the treat-
c
types: PPAR
a
, PPARd, and PPAR
c
. Physiologically, PPARs accounts
agonists warrant development of newer drug with better efficacy
for lipid and glucose homeostasis and thereby, it contributes signif-
and safety profile.4
icantly in metabolic disorders such as obesity, diabetes and
In contrast to a selective PPAR
exhibit insulin sensitizing potential of PPAR
beneficial lipid modulating activities of the PPAR
was thought that PPAR dual or PPAR /d pan agonist would
simultaneously correct insulin resistance and lipid imbalance,
thereby overcome the side effects of selective PPAR agonist and
might work as monotherapy for Type-2 diabetes treatment.5 On
the basis of this hypothesis, in past, several PPAR
dual agonists6
and PPAR
/d pan agonists7 were developed and evaluated. How-
ever some of the developments were terminated because of con-
cerns over cardiovascular safety in clinical trials and propensity to
cause cancer in rodents.8 The unsuccessful efforts to develop dual/
pan agonists and the recent findings that the selective activation of
c
agonist, PPAR
agonist along with
agonist. Thus it
a/c dual agonist
cardiovascular complications. The PPAR
a
is localized in heart, liver
c
and muscles, where it plays an essential role in lipid metabolism
by regulating cellular free fatty acid oxidation and cholesterol traf-
a
a/c
a/c
ficking. Thus, activation of PPARa decreases serum triglycerides
(TG) and increases serum high-density lipoprotein cholesterol
c
(HDL-C), which together restore lipid and glucose homeostasis.1
Fibrates represent an important class of PPAR
ally administered at high doses to get the clinical benefits, mainly
because of their relatively weak affinity for PPAR and poor sub-
type selectivity.2 The PPAR
is highly distributed in skeletal mus-
cle, liver and adipose tissue. Activation of PPAR improves
a
ligands, but usu-
a/c
a/c
a
c
c
glycemic control by increasing insulin sensitivity, via activation
of genes involved in the control of glucose production, transporta-
tion and utilization.3 Pioglitazone and Rosiglitazone are selective
PPAR
alower triglycerides, elevate HDL, and exert insulin sensitizing
effects9 led to the discovery of several potent and selective PPAR
a
agonist as a promising therapeutic option for the treatment of vari-
ous metabolic disorders. In view of these opportunities, identifica-
tion of structural components controlling the selectivity for PPAR
isoforms would be advantageous in designing the next generation
q
ZRC communication No: 319.
Corresponding authors. Tel.: +91 2717 665555; fax: +91 2717 665355.
E-mail addresses: shailesh-chem@msubaroda.ac.in (S.R. Shah), rajeshbahekar@
⇑
of PPARa agonist. Although some research groups have already
zyduscadila.com (R. Bahekar).
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.12.032

P. Zaware et al. / Bioorg. Med. Chem. Lett. 21 (2011) 628–632
629
disclosed potent and selective PPAR
are still under clinical evaluation.11 Recently a potent and selective
PPAR
agonist NS-22011 reported to exert antihyperglycemic and li-
a
agonists,10 these compounds
Aromatic tail
Acidic head
Linker
a
pid modulating effects in animal models but its further development
O
OH
O
is discontinued for unknown reasons. Another compound K11112, a
O
O
N
relatively weak PPARa agonist is presently undergoing clinical trials
O
for the treatment of Type-2 diabetes (Fig. 1).
Balanced PPAR α/γ dual agonist (I)
As a part of our on-going research in the field of PPARs to develop
novel therapeutic agents for the treatment of metabolic disorders,13
earlier, several PPAR agonists were reported, which were developed
bychemicalmodifications, eitherin thelipophilictailpartand/orthe
central spacer region (linker) to modulate agonistic activity and sub-
types selectivity.14,15,16 In the present communication our objective
was to develop oxime containing benzyl 1,3-dioxane-r-2-carboxylic
Replacement of rigid oxazole ring
with flexible liphophilic tail
R
OH
N
O
O
O
O
O
α
Selective PPAR agonist (6a-k)
acid derivatives as highly potent and selective PPAR
designed by bioisostericreplacement of rigid oxazole ring of our pre-
viously reported PPAR
dual agonist (I)13c with a flexible lipophilic
a agonists
Figure 2. Identification of novel lipophilic part for selective PPAR
a
agonistic
a/c
activity.
tail (Fig. 2). The in vitro PPAR agonistic activity and subtypes selec-
tivity of all the test compounds (6a–k) was assessed using in vitro
hPPAR transactivation assay. Furthermore, highly potent and selec-
tive test compound (6c) was subjected for in vivo study to assess its
antihyperlipidemic and antihyperglycemic effects along with its
pharmacokinetic study.
substitution at para position of phenyl ring (6a) may play impor-
tant role in the modulation of potency and selectivity of the test
compounds. In previous communication we reported electron
donating groups improve the PPAR
substitution at the para position of compound 6a with electron
donating groups showed very good PPAR selectivity over PPAR
a selectivity over PPARc.
15 Thus,
Synthesis of title compounds 6a–k was carried out as described
in scheme 1, following modified literature procedure13c and all the
starting materials, procured from commercial source. Various
substituted oximes (2a–k) were synthesized by reacting the corre-
sponding acetophenone (1a–k) with hydroxylamine hydrochloride.
The geometrical structure of all the oximes (2a–k) prepared were
considered to be (E)-isomer because the literature precedent reveals
that the (E)-isomers are thermodynamically more stable than the
corresponding (Z)-isomers.17 Alkylation of oximes (2a–k) with
1,2-dibromoethane in presence of cesium carbonate (Cs2CO3) in
dimethylformamide (DMF) gave the intermediate (3a–k) in good
yield. Finally coupling of (3a–k) with 413c in presence of potassium
carbonate (K2CO3) in DMF gave the esters (5a–k) which on hydroly-
sis under basic condition yielded title compounds 6a–k. The stereo-
chemistry of compound 6 is established as cis isomers, based on 1H
NMR data, wherein the chemical shifts data of compound 6 was
found to be in accordance with the similar compounds reported ear-
lier by us as well as other groups.13c,18 The structure of all the title
compoundsand intermediateswas confirmedby their physical, ana-
lytical and spectral data and the overall percentage yields were
found to be in the range of 50–70%.19
a
c,
as compounds 6b, 6c, and 6f possessing methyl, methoxy and
fluoro groups respectively exhibited excellent potency and selec-
tivity towards PPARa subtype. These findings encouraged us to
study the effect of substituents on both 3- and 4-position of the
phenyl ring. In this regard, we chose methoxy group on both the
positions and synthesized compound 6d, but compound failed to
retain its selectivity as well as potency. Substitution at para
position with electron withdrawing groups exhibited detrimental
effects in vitro, which is evident from the activity of 6e, 6g, and
6h possessing methane sulfonyl, trifluoromethyl and trifluoro-
methoxy groups respectively. Surprisingly compound 6h showed
PPARc selectivity over PPARa. Furthermore, when the flexible
substitution at para position was replaced with rigid bi-cyclic ring
system (tetrahydronaphthyl (6i) and naphthyl (6j)), it resulted in a
weak agonistic activity and poor affinity towards all subtypes
tested. Similarly, compound 6k prepared by replacing phenyl ring
with 3-pyridyl ring showed weak agonistic activity as compared to
6a. Together, these in vitro agonistic activity results across all the
three PPAR subtypes clearly confirmed our hypothesis that the
phenyl oxime group act as a bioisostere of oxazole ring system.
Furthermore, structure–activity relationship (SAR) drawn from
the in vitro study results indicated that electron donating groups
In order to assess the potency and subtypes selectivity, all the
test compounds synthesized (6a–k) were screened in vitro for
hPPAR
cells) according to the procedure described in our earlier publica-
tion.13c The NS-220 (PPAR
), GW-501516 (PPARd), Rosiglitazone
(PPAR ), and compound I (PPAR ) were used as positive controls
a, c, and d agonistic activity (PPAR transfected in HepG2
at para position of phenyl ring is essential for PPAR
The in vivo antihyperlipidemic and antihyperglycemic activities
of lead compound 6c (a highly potent and PPAR selective in vitro)
a selectivity.
a
a
c
a/c
was evaluated in db/db mice. In this model, mice were dosed orally
with either compound 6c or standard compound (NS-220) at 3 and
30 mpk (mg/kg/day) respectively for 7 days and serum triglycer-
ides (TG) and serum glucose (Glucose) were measured. As shown
in Table 2, compound 6c showed significantly reduced TG and glu-
cose and it was found to be comparable with positive controls (NS-
220), at 10-fold lower dose. Similarly, in high cholesterol (HC) fed
(standards) and the in vitro activity results (fold inductions vs
vehicle control (DMSO; 1% solution)) are summarized in Table 1.
As described earlier, our goal was to develop potent and selective
PPARa agonist. In this attempt, we intended to replace the oxazole
ring of dual agonist (compound I) with phenyl oxime group (Fig. 2)
and the initial compound 6a was found to be selective towards
PPARa. Based upon our past experience, we envisioned that
O
Cl
O
N
O
OH
O
Cl Cl
OH
NS-220
K-111
O
Figure 1. Selective PPARa agonist.

630
P. Zaware et al. / Bioorg. Med. Chem. Lett. 21 (2011) 628–632
OCH3
HO
iii
O
R
R
R
Br
O
N
N
i
ii
OH
O
+
O
O
2a-k
1a-k
3a-k
4
O
O
iv
O
OH
O
OCH3
R
R
N
O
O
N
O
O
6a-k
5a-k
O
O
Scheme 1. Reagents and conditions: (i) NH2OHÁHCl, NaOAc, EtOH, H2O, reflux, 2 h, 48–98%; (ii) 1,2-Dibromoethane, Cs2CO3, DMF, heat, 80 °C, 20 h, 19–84%; (iii) K2CO3, DMF,
heat, 80 °C, 20 h, 49–93%; (iv) LiOHÁH2O, CH3OH, THF, H2O, 30 °C, 20 h, 50–70%.
Table 1
Table 2
In vitro hPPAR transactivation activity of test compounds (6a–k)
Antihyperlipidemic and antihyperglycemic activities in db/db micea.
Compd
Dose (mpk/day)
% Change
O
TG
Glucose
O
OH
6c
NS-220
3
30
À53
À54
À45
À43
R
N
O
O
O
a
Male db/db mice (6–8 weeks old) were dosed with test compounds daily for
Compd
R
hPPAR transactivationa,b
7 days and serum triglycerides (TG) and serum glucose (Glucose) were measured.
Values reported as % change of compound-treated group versus vehicle control
(n = 6).
a
(10
l
M)
c
(0.2
l
M)
d (10 lM)
6a
6b
10.79
10.81
1.47
3.05
1.58
Table 3
In vivo antihyperlipidemic activity of compound 6c in HC fed SD ratsa.
2.78
IA
H3C
Compd
Dose (mpk, po/day)
% Change
LDL-C
TG
TC
HDL-C
6c
15.04
3.61
1.44
1.75
H3CO
H3CO
6c
NS-220
3
30
À54
À51
À56
À49
À68
À58
68
62
6d
1.68
a
Male Sprague–Dawely (SD) rats were fed with diet containing high cholesterol
H3CO
(HC) for 15 days then dosed with vehicle or the indicated doses of test compounds,
daily for 14 days by oral gavage (po). Serum triglycerides (TG), total cholesterol
(TC), LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) were measured. Values
represent % change versus vehicle control (n = 9).
6e
6f
1.37
10.49
5.79
IA
1.23
1.62
1.31
1.46
H3CO2S
1.20
2.83
7.39
F
Table 4
Mean pharmacokinetic parametersa of 6c in fasted male wistar rats.
6g
6h
F3C
Compd
Tmax (h)
Cmax (ng/ml)
T1/2 (h)
AUC (0–a) (h ng/ml)
6c
NS-220
0.61 0.02
0.65 0.10
119.61 1.01
40.32 1.19
13.96 1.91
1.99 0.76
1420.01 18.31
99.96 11.41
3.48
F3CO
a
Test compounds were administered orally at 30 mpk, in fasted male wistar rats
6i
6j
1.63
1.76
4.36
3.87
1.25
IA
(n = 6) and plasma concentration was analyzed by LC–MS, values indicate
mean SD.
in db/db mice, compound 6c showed comparable antihyperlipi-
demic activity in HC fed rat model at 10-fold lower dose. Further
to assess the rational behind superior in vivo efficacy of compound
6c over NS-220, single dose (30 mpk, po) comparative pharmacoki-
netic study was carried out in male wistar rats and the data is sum-
marized in Table 4. The compound 6c showed rapid Tmax, good Cmax
and AUC along with extended half-life. Compared to NS-220, com-
pound 6c showed three-fold higher Cmax, fourteen-fold improve-
ment in AUC and seven-fold longer half-life. Thus, improved
pharmacokinetic profile of compound 6c justifies its excellent
pharmacodynamic effects in animal models at a lower dose.
The molecular docking analysis of 6c was carried out to infer its
selectivity profile and critical interactions with the active site of
6k
2.36
1.13
1.31
N
Vehicle
I
NS-220
GW-501516
1.0
14.72
12.72
ND
1.0
7.90
IA
ND
7.22
1.0
IA
2.52
9.24
IA
Rosiglitazone
IA
a
HepG2 cells transfected with pSG5 vector containing cDNA of hPPARa/c/d and
cotransfected with PPRE3-TK-luc. The Luciferase activity determined using fire-fly
luciferase assay and b-galactosidase activity in ELISA reader. Activities presented as
fold induction of PPARa,c, and d activation, wrt vehicle control (DMSO; 1%).
b
IA denotes inactive compounds.
PPARa and PPARc
binding pockets, using GLIDE version 5.6.20 Briefly,
rat model (Table 3), compound 6c exhibited excellent reduction in
TG, total cholesterol (TC) and LDL-cholesterol (LDL-C), along with
increased in the levels of HDL-cholesterol (HDL-C). As observed
the automated docking program implemented in the Schro-
dinger package. The geometry of docked compound (6c) was

P. Zaware et al. / Bioorg. Med. Chem. Lett. 21 (2011) 628–632
631
Figure 3. Molecular docking of 6c into PPARa (A) and c (B) binding pockets: H-bond interactions with amino acids are shown in dashed lines.
subsequently optimized using the LigPrep version 2.6.21 The com-
plexed X-ray crystal structure of the ligand binding domain (LBD)
Further evaluation of this lead compound (chronic pharmacody-
namic studies and toxicological evaluation) is currently under
progress and will be communicated subsequently.
of PPAR
one (2PRG.pdb) were obtained from RCSB Protein Data Bank. As de-
picted in Fig. 3, when 6c was docked into PPAR binding pocket,
a with GW409544 (1k7l.pdb) and PPARc with Rosiglitaz-
a
Acknowledgments
the most stable docking models of 6c adopted a conformation that
allows the carboxylic group to form hydrogen bonds with Tyr314,
Tyr464, and Ser280 (Fig. 3; A), which have been reported to be
Authors are thankful to management of Zydus Group for
encouragement and analytical department for analytical support.
essential interaction for PPAR
ture precedence suggests that interaction of the ligand with
Ser289, His323, Tyr473, and His449 are important for PPAR affin-
ity, as this H-bonding network could stabilize the AF-2 helix in a
conformation which favors the binding of co-activators to PPAR
and consequently, enhance their recruitment.22 When 6c was
docked into PPAR binding pocket the most stable docking model
a
selective compounds.22 The litera-
References and notes
c
1. Raalte, D. H. V.; Pritchard, M.; Li, P. H.; Wasan, K. M. Pharm. Res. 2004, 21, 1531.
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c
c
5. Henke, B. R. J. Med. Chem. 2004, 47, 4118.
of 6c adopted a conformation that only allows the carboxylic group
to form hydrogen bonds with Tyr473 and Ser289. However, other
important residues such as His449 and His323 which are crucial
for PPARc selectivity were found to be away from the ligand and
no H-bond interactions of these amino acids with the carboxylate
6. (a) Henke, B. R.; Blanchard, S. G.; Brackeen, M. F.; Brown, K. K.; Cobb, J. E.;
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group of compound 6c were observed (Fig. 3; B). Thus favorable
in-silico interaction of compound 6c with PPAR
and partial interaction with PPAR binding pocket correlates its
in vitro selectivity profile toward PPAR over PPAR
a binding pocket
c
a
c.
In summary a novel series of oxime containing benzyl-1,3-diox-
ane-r-2-carboxylic acid derivatives with electron donating groups
on para position of phenyl ring emerged as selective PPARa ago-
nists. Lead compound 6c showed excellent antihyperglycemic and
antihyperlipidemic effects in animal models, along with improved
oral bioavailability and in-silico docking studies results were found
be in conformity with in vitro PPAR
study results confirmed that highly potent and selective PPAR
a
selectivity. Our preliminary
ago-
9. (a) Guerre-Millo, M.; Gervois, P.; Raspe, E.; Madsen, L.; Poulain, P.; Derudas, B.;
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a
nist could be viable approach for the safe and effective regulation of
lipid and glucose homeostasis in obese and diabetic patients.

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157.68, 174.81; ESI/MS m/z: 474.2 (M+H)+. Compound 6e: 2-Methyl-c-5-(4-(2-
(((E)-(1-(4-(methylsulfonyl)phenyl)ethylidene)amino)oxy)ethoxy)benzyl)-1,3-
dioxane-r-2-carboxylic acid: oil; yield: 64.0%; purity: 99.64%; IR (CHCl3): 3020,
2976, 1724, 1610, 1512, 1385, 1317, 1246, 1153, 1041, 955 cmÀ1 1H NMR
;
(400 MHz, CDCl3): d 1.54 (s, 3H), 2.26 (s, 3H), 2.28–2.32 (m, 3H), 3.06 (s, 3H) 3.52
(t, J = 10.8 Hz, 2H), 3.89 (dd, J = 12.8 and 4.4 Hz, 2H), 4.26 (t, J = 4.8 Hz, 2H), 4.56
(t, J = 4.8 Hz, 2H), 6.85 (d, J = 8.4 Hz, 2H), 7.00 (d, J = 8.4 Hz, 2H), 7.83 (d, J = 8.4 Hz,
2H), 7.93 (d, J = 8.4 Hz, 2H); 13C NMR: (100 MHz, CDCl3): d 12.85, 25.89, 33.86,
35.20, 44.61, 66.65, 68.23, 73.09, 98.26, 115.50, 127.00, 127.60, 129.68, 130.29,
140.65, 141.85, 153.85, 157.54, 174.60; ESI/MS m/z: 514.13 (M+Na)+. Compound
6f: c-5-(4-(2-(((E)-(1-(4-Fluorophenyl)ethylidene)amino)oxy)ethoxy)benzyl)-2-
methyl-1,3-dioxane-r-2-carboxylic acid: white solid; yield: 70.0%; mp: 80–
81 °C; purity: 98.0%; IR (KBr): 3061, 2935, 2866, 1739, 1610, 1512, 1371, 1240,
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12. Schafer, S. A.; Hansen, B. C.; Volkl, A.; Fahimi, H. D.; Pill, J. Biochem. Pharmacol.
2004, 682, 239.
1105, 935, 837 cmÀ1 1H NMR (400 MHz, CDCl3): d 1.55 (s, 3H), 2.22 (s, 3H), 2.24–
;
2.32 (m, 3H), 3.53 (t, J = 10.8 Hz, 2H), 3.91 (dd, J = 12.4 and 4 Hz, 2H), 4.24 (t,
J = 5.2 Hz, 2H), 4.51 (t, J = 4.4 Hz, 2H), 6.86 (d, J = 8.8 Hz, 2H), 6.99 (d, J = 8.8 Hz,
2H), 7.02–7.07 (m, 2H), 7.60–7.65 (m, 2H); 13C NMR: (100 MHz, CDCl3): d 13.08,
25.94, 33.90, 35.21, 66.75, 68.31, 72.62, 98.20, 114.98, 115.37, 115.59, 128.01,
129.67, 130.15, 132.75, 154.70, 157,68, 162.29, 164.76, 175.21; ESI/MS m/z:
432.20 (M+H)+. Compound 6g: 2-Methyl-c-5-(4-(2-(((E)-(1-(4-(trifluoromethyl)
13. (a) Lohray, B. B.; Bhushan, V.; Reddy, A. S.; Rao, P. B.; Reddy, N. J.; Harikishore,
P.; Vikramadityan, R. K.; Chakrabarti, R.; Rajagopalan, R.; Katneni, K. J. Med.
Chem. 1999, 42, 2569; (b) Reddy, K. A.; Lohray, B. B.; Bhushan, V.; Reddy, A. S.;
Harikishore, P.; Rao, V. V.; Saibaba, V.; Bajji, A. C.; Rajesh, B. M.; Reddy, K. V.;
Chakrabarti, R.; Rajagopalan, R. Bioorg. Med. Chem. Lett. 1998, 8, 999; (c) Pingali,
H.; Jain, M.; Shah, S.; Makadia, P.; Zaware, P.; Goel, A.; Patel, M.; Giri, S.; Patel,
H.; Patel, P. Bioorg. Med. Chem. 2008, 16, 7117; (d) Pingali, H.; Jain, M.; Shah, S.;
Basu, S.; Makadia, P.; Goswami, A.; Zaware, P.; Patil, P.; Godha, A.; Giri, S.; Goel,
A.; Patel, M.; Patel, H.; Patel, P. Bioorg. Med. Chem. Lett. 2008, 18, 5586;
(e) Tudor, C.; Feige, J. N.; Pingali, H.; Lohray, V. B.; Wahli, W.; Desvergne, B.;
Engelborghs, Y.; Gelman, L. J. Biol. Chem. 2007, 282, 4417.
14. Willson, T. M.; Brown, P. J.; Sternbach, D. D.; Henke, B. R. J. Med. Chem. 2000, 43,
527.
15. Pingali, H.; Jain, M.; Shah, S.; Patil, P.; Makadia, P.; Zaware, P.; Kalapatapu, V. V.
M. S.; Jamili, J.; Goel, A.; Patel, M.; Patel, P. Bioorg. Med. Chem. Lett 2008, 18,
6471.
phenyl)-ethylidene)amino)oxy)ethoxy)benzyl)-1,3-dioxane-r-2-carboxylic
oil; yield: 70%; purity: 98.50%; IR (CHCl3): 3580, 3018, 2976, 2930, 1724, 1610,
1512, 1458, 1385, 1327, 1215, 1130, 1059, 930 cmÀ1 1H NMR (400 MHz, CDCl3):
acid:
;
d 1.55 (s, 3H), 2.25 (s, 3H), 2.28 (s, 3H), 3.53 (t, J = 10.8 Hz, 2H), 3.91 (dd, J = 9.6 and
4.0 Hz, 2H), 4.25 (t, J = 4.8 Hz, 2H), 4.54 (t, J = 4.4 Hz, 2H), 6.86 (d, J = 8.4 Hz, 2H),
7.01 (d, J = 8.8 Hz, 2H), 7.61 (d, J = 8.4 Hz, 2H), 7.75 (d, J = 8.4 Hz, 2H); 13C NMR:
(100 MHz, CDCl3): d 12.92, 25.90, 33.92, 35.20, 66.71, 68.21, 72.92, 98.22, 114.97,
125.44, 126.48, 129.69, 130.22, 139.97, 154.34, 157.64, 174.38; ESI/MS m/z:
482.18 (M+H)+. Compound 6h: 2-Methyl-c-5-(4-(2-(((E)-(1-(4-(trifluorometh
oxy)phenyl)ethylidene)amino)oxy)ethoxy)benzyl)-1,3-dioxane-r-2-carboxylic acid
: white solid; yield: 56.0%; mp: 68–70 °C; purity: 98.52%; IR (KBr): 3550, 3149,
16. Pingali, H.; Jain, M.; Shah, S.; Patil, P.; Zaware, P.; Makadia, P.; Pola, S.; Thube,
B.; Patel, D.; Patil, P.; Priyadarshini, P.; Suthar, D.; Shah, M.; Giri, S.; Patel, P.
Bioorg. Med. Chem. Lett 2010, 20, 1156.
17. Yanagisawa, H.; Takamura, M.; Yamada, E.; Fujita, S.; Fujiwara, T.; Yachi, M.;
Isobe, A.; Hagisawa, Y. Bioorg. Med. Chem. Lett. 2000, 10, 373.
2934, 2868, 1736, 1610, 1512, 1452, 1371, 1249, 1157, 1103, 949, 748 cmÀ1 1H
;
NMR (400 MHz, CDCl3): d 1.55 (s, 3H), 2.23 (s, 3H), 2.25–2.31 (m, 3H), 3.53 (t,
J = 10.8 Hz, 2H), 3.93 (dd, J = 14 and 4.0 Hz, 2H), 4.25 (t, J = 5.2 Hz, 2H), 4.52 (t,
J = 4.8 Hz, 2H), 6.86 (d, J = 8.4 Hz, 2H), 7.00 (d, J = 8.4 Hz, 2H), 7.20 (d, J = 8.4 Hz,
2H), 7.67 (d, J = 8.8 Hz, 2H); 13C NMR: (100 MHz, CDCl3): d 12.99, 25.94, 33.88,
35.20, 66.71, 68.32, 72.75, 98.19, 114.91, 119.25, 120.87, 121.81, 127.70, 129.67,
130.19, 135.22, 149.91, 154.40, 157.64, 174.38; ESI/MS m/z: 498.18 (M+H)+.
Compound 6i: 2-Methyl-c-5-(4-(2-(((E)-(1-(5,6,7,8-tetrahydronaphthalen-2-yl)
ethylidene)amino)oxy)ethoxy)benzyl)-1,3-dioxane-r-2-carboxylic acid: oil; yield:
64.0%; purity: 99.47%; IR (CHCl3): 3300, 3018, 2932, 1724, 1512, 1385, 1246,
18. Harabe, T.; Matsumoto, T.; Shioiri, T. Tetrahedron Lett. 2007, 48, 1443.
19. Spectroscopic analysis of the compounds 6a–k. Compound 6a: 2-Methyl-c-5-(4-(2-
(((E)-(1-phenylethylidene)amino)oxy)ethoxy)benzyl)-1,3-dioxane-r-2-carboxylic
acid. White solid; yield: 70.0%; mp: 82–84 °C; purity: 98.79%; IR (KBr): 3414,
3018, 2939, 2663, 2532, 1713, 1612, 1510, 1445, 1369, 1271, 1145, 959 cmÀ1 1H
;
NMR (400 MHz, CDCl3): d 1.55 (s, 3H), 2.24(s, 3H), 2.27 (s, 3H), 3.53 (t, J = 10.8 Hz,
2H), 3.93 (dd, J = 12 and 3.6 Hz, 2H), 4.25 (t, J = 5.2 Hz, 2H), 4.52 (t, J = 4.4 Hz, 2H),
6.86 (d, J = 8.8 Hz, 2H), 7.00 (d, J = 8.8 Hz, 2H),7.34–7.38 (m, 2H), 7.62–7.64 (m,
2H);13CNMR: (100 MHz, CDCl3):d13.13, 25.93, 33.91, 35.21, 66.79, 68.30, 72.58,
98.22, 115.00, 126.24, 128.53, 129.29, 129.66, 130.13, 136.66, 155.77, 157.70,
175.21; ESI/MS m/z:414.20 (M+H)+; 6b: 2-Methyl-c-5-(4-(2-(((E)-(1-(p-tolyl)eth
ylidene)amino)oxy)ethoxy)benzyl)-1,3-dioxane-r-2-carboxylic acid: white solid;
yield: 67.0%; mp: 92–94 °C; purity: 99.68%; IR (KBr): 3414, 3290, 2924, 2870,
1145, 1041, 929 cmÀ1 1H NMR (400 MHz, CDCl3): d 1.55 (s, 3H), 1.77–1.80 (m,
;
4H), 2.20 (s, 3H), 2.26–2.30 (m, 3H), 2.76 (d, J = 6.0 Hz, 4H), 3.52 (t, J = 10.8 Hz,
2H), 3.92 (dd, J = 14.4 and 4.0 Hz, 2H), 4.24 (t, J = 4.8 Hz, 2H), 4.51 (t, J = 4.8 Hz,
2H), 6.86 (d, J = 8.4 Hz, 2H), 6.99 (d, J = 8.4 Hz, 2H), 7.05 (d, J = 8.0 Hz, 1H), 7.32–
7.35 (m, 2H); 13C NMR: (100 MHz, CDCl3): d 13.16, 23.25, 25.86, 29.37, 29.59,
33.34, 35.35, 60.82, 68.27, 72.43, 98.21, 115.09, 123.36, 126.85, 129.28, 129.63,
130.04, 133.85, 137.28, 137.47, 138.64, 155.96, 157.73, 174.81; ESI/MS m/z:
468.34 (M+H)+. Compound 6j: 2-Methyl-c-5-(4-(2-(((E)-(1-(naphthalen-2-yl)
ethylidene)amino)oxy)ethoxy)benzyl)-1,3-dioxane-r-2-carboxylic acid: white
solid; yield: 53.0%; mp: 136–137 °C; purity: 99.21%; IR (KBr):3500, 3059,
2965, 2853, 1751, 1610, 1510, 1454, 1387, 1246, 1149, 1120, 1041, 964,
1740, 1718, 1639, 1512, 1460, 1367, 1151, 1033, 655 cmÀ1 1H NMR (400 MHz,
;
CDCl3):d1.55 (s, 3H), 2.22 (s, 3H), 2.30 (s, 3H), 2.35(s, 3H), 3.52(t, J = 10.4 Hz, 3H),
3.91 (dd, J = 12 and 3.6 Hz, 2H), 4.24 (t, J = 4.8 Hz, 2H), 4.50 (t, J = 4.4 Hz, 2H), 6.86
(d, J = 8.4 Hz, 2H), 6.99 (d, J = 8.4 Hz, 2H), 7.16 (d, J = 8.0 Hz, 2H), 7.53 (d,
J = 8.0 Hz, 2H); 13C NMR: (100 MHz, CDCl3): d 13.08, 21.38, 25.91, 33.90, 35.20,
66.79, 68.27, 72.47, 98.23, 114.98, 126.12, 129.22, 129.64, 130.09, 133.80,
139.30, 155.73, 157.70, 174.83; ESI/MS m/z: 428.21 (M+H)+. Compound 6c: c-5-
(4-(2-(((E)-(1-(4-Methoxyphenyl)ethylidene)amino)oxy)ethoxy)benzyl)-2-methyl
-1,3-dioxane-r-2-carboxylic acid: off white solid; yield: 63.0%; mp: 108–109 °C;
868 cmÀ1 1H NMR (400 MHz, CDCl3): d 1.55 (s, 3H), 2.27–2.52 (m, 3H), 2.35 (s,
;
3H) 3.52 (t, J = 10.8 Hz, 2H), 3.93 (dd, J = 10.8 and 4.0 Hz, 2H), 4.29 (t, J = 5.2 Hz,
2H), 4.57 (t, J = 4.8 Hz, 2H), 6.89 (d, J = 8.4 Hz, 2H), 7.00 (dd, J = 8.4 and 2.8 Hz,
2H,), 7.47–7.51 (m, 2H), 7.79–7.87 (m, 3H), 7.90 (dd, J = 8.8 and 1.6 Hz, 1H), 7.99
(s, 1H); 13C NMR: (100 MHz, CDCl3): d 12.89, 25.94, 33.90, 35.10, 66.83, 68.34,
72.71, 98.13, 115.01, 123.60, 125.97, 126.48, 126.73, 127.77, 128.13, 128.60,
129.67, 130.12, 133.23, 133.80, 133.96, 155.52, 157.72, 174.83; ESI/MS m/z:
486.19 (M+Na)+. Compound 6k: 2-Methyl-c-5-(4-(2-(((E)-(1-(pyridin-3-
yl)ethylidene)amino)oxy)ethoxy)benzyl)-1,3-dioxane-r-2-carboxylic acid: oil;
yield: 62.0%; purity: 99.05%; IR (CHCl3): 3387, 3018, 2976, 1739, 1612, 1512,
purity: 98.79%; IR (KBr): 3348, 2995, 2852, 1764, 1720, 1606, 1512, 1190 cmÀ1
;
1H NMR (300 MHz, CDCl3): d 1.55 (s, 3H), 2.17 (s, 3H), 2.21-2.30 (m, 3H), 3.52 (t,
J = 10.56 Hz, 2H), 3.82 (s, 3H), 3.93 (dd, J = 12.32 and 5.2 Hz, 2H), 4.25 (t,
J = 5.13 Hz, 2H), 4.49 (t, J = 4.71 Hz, 2H), 6.87 (dd, J = 8.82 and 5.25 Hz, 4H), 7.00
(d, J = 8.49 Hz, 2H), 7.59 (t, J = 8.85 Hz, 2H); 13C NMR: (100 MHz, CDCl3): d 21.43,
21.58, 25.88, 29.83, 33.93, 35.23, 66.62, 68.20, 72.71, 98.22, 114.96, 128.04,
128.12, 128.25, 128.94, 129.07, 129.44, 129.63, 130.10, 130.24, 133.43, 133.73,
136.77, 139.06, 139.63, 157.64, 157.78, 175.00; ESI/MS m/z: 444.2 (M+H)+.
Compound 6d: c-5-(4-(2-(((E)-(1-(3,4-Dimethoxyphenyl)ethylidene)amino)oxy)
ethoxy)benzyl)-2-methyl-1,3-dioxane-r-2-carboxylic acid: oil; yield: 61.0%;
purity: 99.0%; IR (CHCl3): 3385, 3018, 2937, 1739, 1610, 1512, 1406, 1249,
1385, 1246, 1151, 1043, 929 cmÀ1 1H NMR (400 MHz, CDCl3): d 1.55 (s, 3H), 2.25
;
(s, 3H), 2.28–2.35 (m, 1H), 2.41 (d, J = 6.4 Hz, 1H), 3.61 (t, J = 11.6 Hz, 2H), 3.90
(dd, J = 12.4 and 4.4 Hz, 2H), 4.31(t, J = 4.8 Hz, 2H), 4.55 (t, J = 4.8 Hz, 2H), 6.83 (d,
J = 8.8 Hz, 2H), 6.98 (dd, J = 10.4 and 2.0 Hz, 2H), 7.40 (dd, J = 8.0 and 4.8 Hz, 1H),
7.96 (dd, J = 9.6 and 1.6 Hz, 1H), 8.57 (d, J = 4.0 Hz, 1H), 8.82 (s, 1H); 13C NMR:
(100 MHz, CDCl3): d 12.57, 26.06, 33.97, 35.28, 66.63, 68.07, 73.02, 98.64, 115.17,
124.09, 129.75, 130.48, 133.24, 135.05, 145.72, 148.00, 152.31, 157.45, 173.68;
ESI/MS m/z: 415.21 (M+H)+.
1057, 929, 869 cmÀ1 1H NMR (400 MHz, CDCl3): d 1.54 (s, 3H), 2.22 (s, 3H), 2.29
;
(s, 3H), 3.53 (t, J = 10.4 Hz, 2H), 3.90 (m, 8H), 4.24 (s, 2H), 4.50 (s, 2H), 6.83–6.87
(m, 3H), 6.99 (d, J = 7.2 Hz, 2H), 7.14 (d, J = 8.0 Hz, 1H), 7.28 (s, 1H); 13C NMR:
(100 MHz, CDCl3): d 12.98, 25.88, 33.90, 35.20, 56.02, 66.80, 68.22, 72.46, 98.30,
108.84, 110.70, 114.96, 119.37, 129.39, 129.64, 130.13, 148.91, 150.23, 155.33,
20. GLIDE 5.6, Schrodinger, LLC, New York, NY, 2010.
21. LigPrep 2.6, Schrodinger, LLC, New York, NY, 2010.
22. Zoete, V.; Grosdidier, A.; Michielin, O. Biochim. Biophys. Acta 2007, 1771,
915.